412 TRANSIT OF VENUS, 1874. KERGUELEN ISLAND. OBSERVATORY BAT. 



observatories have been used. The reductions from mean to apparent places 

 have been taken from the Nautical Almanac for all stars found in that work. 



The refractions have been computed by the tables forming the Appendix 

 to the Greenwich Observations for 1853, and then reduced in the proportion 

 of 1 to 0-9947. "Whether this reduction was proper or not is of little 

 importance, as stars were observed North and South of the zenith. 



An aneroid barometer, suspended in the Altazimuth observatory, was read 

 in connection with the zenith distance observations ; in addition to which a 

 mercurial barometer, Adie M 33, properly tested before leaving England, 

 was suspended in the observer's dwelling-house, and read every four hours. 

 These readings generally afford the means of ascertaining the error of the 

 aneroid with sufficient accuracy, as shown by the following table : 



Number Correction 



Month. of to 



Comparisons. Aneroid. 



in- 



1874, April 8 0-29 



,, November 14 0*34 



, , December 4 o'3i 



1876, January 9 0-29 



, , February 1 6 o 32 



The correction O ia> 32 has been applied throughout. 



From the observations (of which it is unnecessary to print the details) we 

 have the following result for the co-latitude of the Altazimuth pier at 

 Observatory Bay : 



O I II 



By 26 stars North of zenith, co-latitude is 40. 34. 48'2 S. 

 , , 8 , , South , , , , 40. 34. 48'0 S. 



Adopted latitude... 49. 25'. 11"'9 S. 



OBSERVATIONS OF AZIMUTH. 



The horizontal circle, 15 inches in diameter, fixed upon the tripod stand, 

 is divided into spaces of 5', and is read by the four microscope-micrometers 

 attached to the revolving body. It was intended that a revolution of the 

 screw of each micrometer should be one minute, and the screw-heads were 

 divided on silver into 60 parts or seconds. The stationary portion of the 



